When you smoke, it isn’t just your own health you’re putting in jeopardy. The health risks associated with passive smoking are generally less well known than those of direct smoking – but they have been proved beyond a doubt.
What is passive smoking?
Passive smoking occurs when anyone (including the smoker) inhales tobacco smoke from the environment, as opposed to directly inhaling from a cigarette. This environmental or ‘second-hand’ smoke comprises two parts: smoke exhaled by a smoker (mainstream smoke) and smoke produced from the tip of a burning cigarette (side-stream smoke). Smokers only inhale about 15% of the smoke from a cigarette. The rest enters the atmosphere.
How dangerous is passive smoking?
Second-hand smoke contains all the same carcinogenic and toxic chemicals that the smoker inhales, but at even greater levels. The toxins in second-hand smoke aren't filtered as they are when inhaled directly from the cigarette. Also, because side-stream smoke is formed at lower temperatures, it gives off even larger amounts of some harmful substances. It is estimated that a non-smoker in a smoke-filled room for eight hours will inhale the equivalent amount of carcinogens to smoking 36 cigarettes.
The immediate negative effects of second-hand smoke may include eye irritation, headache, nasal discomfort and sneezing, cough, sore throat, nausea, dizziness, and increased heart rate and blood pressure.
Passive smokers are also at increased risk for nearly all the medical conditions associated with smoking. Lung cancer, heart disease, asthma and other respiratory problems, infertility and impotence have been particularly strongly linked to passive smoking.
Exposure to second-hand smoke and smoking while pregnant are both linked to miscarriage, low birth weight and stillbirths. Several studies have also shown that children of parents who smoke have a greater chance of dying of sudden infant death syndrome (SIDS).
Passive smoking and cancer
Several studies have indicated that second-hand smoke can cause lung cancer in non-smoking spouses of heavy smokers as well as in non-smokers exposed to smoke in the workplace.
Non-smokers exposed to second-hand smoke have a 18-32% higher risk of developing lung cancer than those not exposed. The longer the exposure period, the greater the risk.
Second-hand smoke seems to stimulate tumour growth and angiogenesis, the abnormal formation of new blood vessels feed tumours with the blood supply they need to grow and spread.
Passive smoking and heart disease
Even short-term exposure to passive cigarette smoke has a significant impact on the hearts of non-smokers. Only 30 minutes of exposure to second-hand smoke can damage a non-smoker's heart and increases the risk of heart disease by 30%.
The toxins exhaled by smokers cause decreased oxygen to the heart, increased blood pressure and heart rate, increased blood clotting and damage to lining of the blood vessels.
Passive smoking and reproductive problems
Spending time in a smoker’s company can significantly reduce a woman's chance of conceiving. A woman who lives with a 20-or-more-a-day smoker has her chance of becoming pregnant lowered by 34%. Conception will be even harder for a woman who smokes and is exposed to passive smoke.
Middle-aged men who are heavily exposed to second-hand smoke have nearly twice the risk of impotence.
Passive smoking and respiratory problems
Asthma sufferers who are exposed to second-hand smoke are more likely to experience wheezing, coughing and shortness of breath. Children with asthma are especially at risk as the side-effects of passive smoking affect their airways faster.
Second-hand smoke has also been linked to a number of other respiratory health problems, including pneumonia, sinus infection and impaired lung function. Children whose parents smoke are more likely to suffer from colds, pneumonia, bronchitis, ear infections, coughing and allergies. If the children already have asthma or allergies, a parent's smoking may cause these conditions to get worse.
- Olivia Rose-Innes, EnviroHealth Editor, Health24, updated November 2010
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